Conventionally, a distance measurement system that uses an indirect time of flight (ToF) method has been known. Such a distance measurement system involves a sensor that can sort signal charges, which are obtained when light reflected as active light emitted with the use of a light emitting diode (LED) or a laser at a certain phase is incident on a subject is received, into different regions at high speed.
Thus, a technology has been proposed in which, for example, a wide range of region in a substrate can be modulated when at high speed such that a voltage directly applied to a substrate of a sensor to generate current in the substrate (see, for example, Patent Document 1). Such a sensor is also called a current assisted photonic demodulator (CAPD) sensor.
The CAPD sensor includes application electrodes to which a voltage is applied and a suction electrode for collecting charges. When a voltage is applied to one of the two application electrodes, which are paired, current is generated between the application electrodes, and a signal charge generated by photoelectric conversion is guided to and collected by the suction electrode.